Well I can say that most app developers use a pirated version of windoes
Very wrong, many indie developers who plan to go big, startup or entrepreneurs don't use pirated software.
Corps, schools, organizations strictly don't use pirated software.
In fact Indies pay for their entire toolchain.
Its only the casual developer for learning purpose may use pirated software.
PCs, Laptops from hp, dell, toshiba etc come with licensed Windows usually!
Again how Do I know this about indie developers ? Well as a developer myself, I meet fellow developers at conferences.. not just in india btw

. We discuss things. Everyone pays licensing costs. My friends used to ask me to buy them discounted photoshop... but now with everything going subscription, developers are preferring renting it when required in the development cycle.
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So that's decided, So I guess I have to use both.
Yes, this is it, you have to invest everywhere! Mac for iOS, Windows, Linux if you want to make linux apps..
Android development, you can develop in Windows and test on Android device.